Supercapacitor performance of polymer-in-salt electrolyte/water-in-polymer salt electrolyte synthesized by complexing glutaraldehyde crosslinked corn starch with Mg(ClO4)2

Energy devices with high energy/power density are the need of the day, and to achieve the same, electrolytes with faster ion transport and wider electrochemical stability window are required. Polymer-in-salt electrolytes (PISEs) are predicted to have the better required electrochemical properties in comparison to salt-in-polymer electrolytes (SIPEs), but desired success is still to be achieved due to recrystallization problems. PISEs suffer from poor mechanical and/or electrochemical properties along with aging effects as well; hence, special efforts are required to reduce the crystallinity of PISEs. The present paper discusses a crosslinked corn starch complexed with Mg(ClO₄)₂ which not only has desired electrochemical properties but is also flexible. XRD study confirms the absence of crystalline nature, without any extra efforts to reduce it. Synthesized PISEs have high conductivity (~0.01 Scm⁻¹), wide ESW (> 3 V), and low relaxation time (µs) along with being economical. Supercapacitors fabricated using this novel PISE with laboratory synthesized activated carbon (from leaves and corn starch) have shown good specific capacitance (~ 20 Fg⁻¹ and ~ 45 Fg⁻¹, respectively). The power density is of the order of kW kg⁻¹, which is quite high in comparison to other reports. The shape of CV and LSV is strongly influenced by the salt concentration, i.e., by the ion-cluster size, and is also affected by the volume/size of the activated carbon pores.